Metallized condenser paper



Dec, 22, 1942, w. DORN I 2,305,849

METALLIZED CONDENSER PAPER Filed Sept. 50, 1938 Patented Dec. 22, 1942METAILIZED CONDENSER PAPER Walter Dom, Stuttgart, Germany; vested in theAlien Property Custodian Application September 80, 1938, Serial No.232,698

In Germany October 4, 1937 60lalms.

when using metal paper for manufacturing condensers in which the faultypoints inthe dielectric become innocuous by the burning out of the metalcoating around the faulty points. it is necessary to ensure that thenergy liberatedon burning out in the event of a puncture is not toolarge, since otherwise mechanical destruction can occur in the winding.The results of experiments have shown that by using metals with fairlylarge conductivity, it is possible to make the metal layers so thin, forinstance 0.1;, that the burning out process requires a particularlysmall energy. Very good results are obtained with silver or copper.Still better suited are aluminum or magnesium since-these metals, withreference to the units of weight, have the smallest specific resistanceof all metals which are still suillciently stable. It is thus especiallyadvantageous to use aluminum or magnesium, as a metal coating inmanufacturing condensers of the said type.- Zinc and cadmium are alsosuitable,

However, an obstacle to the use of these metals is their extraordinarytendency to oxidation, whereby difllculties arise in the production ofthe electrical connections.

An object of the present invention is to provide a metallized dielectricmaterial of the type described, in which the advantages of oxidisablemetals such as aluminum, magnesium, zinc or cadmium can be realisedwithout the accompany ing disadvantage of the said metals becomingoxidized. I v

- In the manufacture of condensers, according to the present invention ametallized paper isv used having a coating of a base metal inelectrically conductive connexion with an adjacent coating-of noblemetal, that is to say, having a relatively high resistance to oxidation,e. g. silver 009F By this means a layer or a more noble metalis'disposedalong the edge of the paper band which later serves for theconnexion. Copper is especially to be recommended on account of its goodconductivity, its fairly noble properties and low cost. a y

It is of advantage to vaporise this copper layer on in vacuodirectlyafter the application or the aluminum or magnesium without the bandsbeing previously brought into contact with the air. The magnesium oraluminum has then not yet become coated with a him of oxide and combinesvery readily with the copper to form a magnesium bronze or aluminumbronze. It is suitable to gradually at the point of combination with thenoble metal and to allow the copper layer to commence gradually. 80 thatthe resulting metal thickness also remains approximately constant.

at the transition layer. By gradually" is intended to be understood inthis process a width of transition of at least 1 mm. It is appropriateto provide the vaporising point for the copper directly behind that forthe aluminum, the vaporlsing nozzles being appropriately allowed to runat an acute angle at the point of the transition layer.

In the drawing, the edge part of a paper band metallized according tothe process just described is illustrated in a greatly enlarged sectionperpendicular to the edge and to the surface. The paper hand is shown byi, the base metal coating by 2 and the nobler metal coating by 3.

I declare that what I claim is:

i. la an electrostatic condenser, a metallized paper comprising a paperlayer carrying an adherent metallic coating of substantially uniformthickness comprising a strip of metal highly reclstant to oxidationselected from the group consisting of silver, and copper, lying parallelto a margin 02 the paper layer, and a strip of base metal selected fromthe group consisting of magnesium, aluminum. cadmium, and zinc, lyingnext to the-highly resistant metal strip on the side away from saidmargin of the paper, said highly resistant and base metal strips havingtheir meeting edges in continuous conductive connection with each other.

2. In an electrostatic condenser, a metallized 35 of zinc lying next tothe noble metal strip on the side away from said margin of the paper,said silver and zinc strips having their meeting edges in continuousconductive connection with each other.

a. In an electrostatic condenser, a metallized paper comprising a paperlayer carrying an adherent metallic coating of substantially uniformthickness comprising a strip of copper lying parallel to a margin of thepaper layer, and a strip of sine lying nextto the-noble metal strip onthe allow the layer of the base metal to terminate side away irom saidmargin of the'paper, said copper and zinc strips having their meetingedges in continuous conductive connection with 'each other.

4. In an electrostatic condenser, a metallized paper comprising a paperla'yer carrying an adherent metallic coating of substantially uniformthickness comprising a strip or copper lying parallel to a margin of thepaper layer, and a strip of base metal selected from the groupconsisting of aluminum, magnesium, cadmium, and 'zinc,

. lying next to the copper strip on the side away from said margin ofthe paper, said copper and base metal strips having their meeting edgesin continuous conductive connection with each other.

5. In an electrostatic condenser, a metallized band 01. fiexibledielectric material carrying an' adherent metallic coating ofsubstantially uniform thickness comprising a strip of base metalselected from the group consisting of magnesium, aluminum, cadmium, andzinc, and a strip of metal relatively highly resistant to oxidationselected from the grou consisting of silver, and copper, said highlyresistant metal strip formlocated between said zinc strip and at leastone longitudinal edge of the band, said strips having their adjacentmargins united by metal consisting of an alloy of the adjacent copperand zinc metals along a slope the plane of which meets the surface ofsaid band in an acute angle.

WALTER DORN.

